Electric motor, compressor including the same, and method of manufacturing electric motor

ABSTRACT

In an electric motor, an n-th layer of windings includes: a first winding portion wound from a radially outer side of the stator to a radially inner side of the stator so as to form a gap dimensioned to one pitch or more of the windings at a preset position; and a second winding portion wound from the radially inner side of the stator to the radially outer side of the stator in a continuous manner from the first winding portion so as to fill in the gap, the second winding portion crossing the first winding portion. The gap is formed at a position that is at an intermediate portion of the tooth in a stator radial direction and that is a position at which the windings switch from the n-th layer to an (n+1)th layer.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. utility applicationSer. No. 14/894,833filed on Nov. 30, 2015, which is a U.S. nationalstage application of International Application No. PCT/JP2013/079372filed on Oct. 30, 2013, the disclosure of which is incorporated hereinby reference.

TECHNICAL FIELD

The present invention relates to an electric motor, a compressorincluding the same, and a method of manufacturing an electric motor.More specifically, the present invention relates to a method of windingwindings to be wound on an insulator.

BACKGROUND ART

A compressor to be used to compress refrigerant and the like includes,for example, a shell, which is an airtight container, a stator fixed onan inner peripheral surface of the shell, a rotor connected to a shaftand rotatably supported thereon, and a compression mechanism to whichrotation of the rotor is transmitted via the shaft, the transmittedrotational power being used to compress refrigerant.

Note that, the stator includes an iron core formed by laminating aplurality of magnetic steel sheets, for example, an insulator formed ofan insulating material such as a resin, and windings wound on theinsulators. The windings are wound on the insulator in a plurality oflayers. Various methods have been proposed as the winding method.

For example, a stator has been proposed that employs a winding methodthat effectively utilizes dead space formed between the windings of twoadjacent cores (see, e.g., Patent Literature 1). The technologydisclosed in Patent Literature 1 improves the winding space factor byemploying a method of winding two adjacent cores asymmetrically toeffectively utilize dead space.

As a method for suppressing positional deviation of a radially innermostpart of the winding on, for example, it is conceivable to employ amethod of winding two adjacent cores asymmetrically such as in thetechnology disclosed in Patent Literature 1, and then to form a wallfrom the windings of adjacent cores so as to prevent the position of theradially innermost winding from deviating.

Further, a stator has been proposed in which the windings are wound onthe core while leaving a gap in any of the winding layers foraccommodating the windings, and then the windings are wound whilefilling the gap (see, e.g., Patent Literatures 2 and 3). In PatentLiteratures 2 and 3, during the winding of the outermost layer of therespective windings, the windings are wound in an inward direction froma radially outer side of the stator to a radially inner side of thestator while leaving a gap having a dimension equal to a preset pitchamount. Further, after the windings are wound inwards, the windings arewound in an outward direction from the radially inner side of the statorto the radially outer side of the stator so as to fill in the gap formedduring the inward winding. Thus, in Patent Literatures 2 and 3,unwinding of the windings is suppressed by winding in both an inwarddirection and in an outward direction, which causes the windings on theoutermost layer to cross each other.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 2003-333783 (see, for example, paragraphs [0061]-[0066], FIG. 19 andFIG. 20)

Patent Literature 2: Japanese Unexamined Patent Application PublicationNo. 2005-12876 (see, for example, Abstract and FIG. 6)

Patent Literature 3: Japanese Unexamined Patent Application PublicationNo. 2009-240010 (see, for example, Abstract)

SUMMARY OF INVENTION Technical Problem

With the method for suppressing unwinding of the windings using thetechnology disclosed in Patent Literature 1, the windings of adjacentcores serve as a wall for preventing unwinding, and hence a windingdesign is necessary that keeps the gap between the adjacent cores asclose to zero as possible. As a result, consideration needs to be givento the wire diameters that are available in currently produced windings,the number of turns required by the winding design, manufacturingvariation among windings, processing variation among windings, and otherfactors, and hence there is a problem in that the stator design becomesmore complex.

In this case, for a winding that is sandwiched by a winding on theradially inner side and a winding on the radially outer side thereof,the winding position is determined by the winding on the radially innerside and the winding on the radially outer side, and hence the positionof the winding is less susceptible to deviation. However, for theradially innermost winding, there is a winding on the radially outerside, but there is no winding on the radially inner side for determiningthe position of the innermost winding. In particular, when the windingsare not wound as far as the radially innermost side of the core(insulator), the radially innermost winding is also separated from thewall on the radially innermost side of the core (insulator). As aresult, with the technologies disclosed in Patent Literatures 2 and 3,when an external force or vibrations, for example, are applied on thestator, the position of the radially innermost winding may deviate tothe radially inner side of the stator, which can cause the windings thathave been wound to unwind.

Note that, in addition to the technologies disclosed in PatentLiteratures 1 to 3, other methods for suppressing unwinding of thewindings may include impregnating the core having the windings woundthereon with varnish, integrally molding the windings with the core byresin molding, and adhering the windings and the core to each other withan adhesive or the like. However, when those methods are used, there isa problem in that manufacturing costs are increased by the cost of thevarnish, for example.

The present invention is directed to solving the above-mentionedproblems. It is an object of the present invention to provide anelectric motor capable of suppressing the unwinding of windings wound onan insulator while suppressing design complexity of a stator andsuppressing an increase in manufacturing costs, a compressor includingthe electric motor, and a method of manufacturing an electric motor.

Solution to Problem

According to one embodiment of the present invention, there is providedan electric motor, An electric motor including a stator, the statorincluding a core, the core including a tooth on which a winding is woundat a preset pitch to form a plurality of layers of the winding, thewinding of one of the layers being angled to the winding of another oneof the layers adjacent to the one of the layers, wherein an n-th layerof the winding comprises: a first winding portion wound from a radiallyouter side of the stator to a radially inner side of the stator with agap between one turn and another at a preset position, the gap beingdimensioned to one pitch or more of the winding; and a second windingportion wound from the radially inner side of the stator to the radiallyouter side of the stator in a continuous manner from the first windingportion to fill in the gap, the second winding portion crossing thefirst winding portion, and the gap is at a position at an intermediateportion of the tooth in the radial direction of the stator, the positionbeing a position at which the winding turns over from the n-th layer toan (n+1)th layer.

Advantageous Effects of Invention

The electric motor according to the one embodiment of the presentinvention has the above-mentioned configuration, and thus may suppressthe unwinding of the windings wound on the insulator while suppressingdesign complexity of the stator and suppressing an increase inmanufacturing costs.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration example diagram of a compressorincluding an electric motor according to an embodiment of the presentinvention.

FIG. 2 is an illustration of a stator of the electric motor according tothe embodiment of the present invention as viewed from above the stator.

FIG. 3 is an illustration of the stator of the electric motor accordingto the embodiment of the present invention as viewed from the side ofthe stator.

FIG. 4 are schematic configuration example diagrams of an insulator andthe like mounted on the stator illustrated in FIG. 2.

FIG. 5 are schematic configuration example diagrams of a state in whichwindings are wound on the insulator illustrated in FIG. 3.

FIG. 6 is an illustration of the windings wound on the insulator of theelectric motor according to the embodiment of the present invention.

FIG. 7 is an illustration illustrating a first winding portion of thewindings illustrated in FIG. 6 and a gap.

FIG. 8 is an illustration illustrating a second winding portion of thewindings illustrated in FIG. 6.

FIG. 9 is an illustration regarding a related-art method of windingwindings.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention is now described with referenceto the drawings.

Embodiment

FIG. 1 is a schematic illustration of exemplary configuration of acompressor 100 including an electric motor 1 b according to anembodiment of the present invention. FIG. 2 is an illustration of astator 2 of the electric motor 1 b according to this embodiment asviewed from above the stator 2. FIG. 3 is an illustration of the stator2 of the electric motor 1 b according to this embodiment as viewed fromthe side of the stator 2.

The electric motor 1 b according to this embodiment includes amodification that enables unwinding of winding(s) 6 wound on aninsulator(s) 7 to be suppressed, while suppressing design complexity ofthe stator 2 and suppressing an increase in manufacturing costs(hereafter, windings 6 or insulators are referred to collectively aswindings 6 or insulators 7, or may be referred to the winding 6 or theinsulator 7 as a separate entity).

[Explanation of Configuration]

The compressor 100 includes an airtight container 1, a suction pipe 1 gfor supplying refrigerant into the airtight container 1, a fluidreservoir container 1 h connected to the suction pipe 1 g, a compressionmechanism 1 d connected to the suction pipe 1 g, and configured tocompress refrigerant, a shaft 1 c configured to rotate, an electricmotor 1 b including a rotor 3, which is connected to the shaft 1 c, andthe stator 2 configured to rotate the rotor 3, and a discharge pipe 1 ffor discharging compressed refrigerant from the airtight container 1. Inthis embodiment, the compressor 100 is illustrated as an example of arolling piston compressor.

(Airtight Container 1)

The airtight container 1 constitutes an external shell of the compressor100. The airtight container 1 includes at least the compressionmechanism 1 d, the electric motor 1 b, and other members. The airtightcontainer 1 is formed of an upper shell 1 a 1 and a lower shell 1 a 2.The lower shell 1 a 2 forms the external shell of a body portion and alower portion of the compressor 100. The upper shell 1 a 1 is an endportion-side shell (a shell at an end portion of the shell) forming anupper portion of the airtight container 1. The upper shell 1 a 1 has abowl shape formed by drawing, for example. The discharge pipe 1 farranged to communicate the interior and the exterior of the airtightcontainer 1 is connected to the upper shell 1 a 1. Further, although notshown in FIG. 1, a glass terminal that causes current to flow to theelectric motor 1 b is installed on the upper shell 1 a 1.

The lower shell 1 a 2, which forms an intermediate portion and a lowerportion of the airtight container 1, has a bottomed tubular shape havinga closed lower side, for example. In other words, the lower shell 1 a 2has an opening on an upper side into which the upper shell 1 a 1 ispress-fitted. The lower side of the lower shell 1 a 2 is closed, whichallows refrigerating machine oil used to reduce the sliding friction ofthe compression mechanism 1 d to accumulate in the lower shell 1 a 2.The suction pipe 1 g configured to supply refrigerant into the airtightcontainer 1 is connected to the lower shell 1 a 2. Further, the stator 2of the electric motor 1 b is mounted to an inner peripheral surface ofthe lower shell 1 a 2. The compression mechanism 1 d is mounted to alower side of the surface to which the stator 2 is mounted, namely, theinner peripheral surface of the lower shell 1 a 2.

(Suction Pipe 1 g and Fluid Reservoir Container 1 h)

One end of the suction pipe 1 g is connected to the lower shell 1 a 2 ofthe airtight container 1 so as to be in communication with a cylinder ofthe compression mechanism 1 d. The other end of the suction pipe 1 g isconnected to the fluid reservoir container 1 h. The fluid reservoircontainer 1 h has a function as a muffler for reducing the noise of therefrigerant flowing into the compressor 100. Further, the fluidreservoir container 1 h also has a function as an accumulator capable ofaccumulating liquid refrigerant. One end of the fluid reservoircontainer 1 h is connected to the suction pipe 1 g.

(Compression Mechanism 1 d)

The compression mechanism 1 d is configured to compress refrigerantsupplied via the fluid reservoir container 1 h and the suction pipe 1 g,and release compressed refrigerant into the airtight container 1. Thecompression mechanism 1 d is mounted to an inner surface of the lowershell 1 a 2. The compression mechanism 1 d includes a cylinderconfigured to compress refrigerant supplied from the suction pipe 1 g, apiston configured to slidably rotate in the cylinder, and other members.The piston is connected to the shaft 1 c, and is configured to moveeccentrically in the cylinder. Bearings 1 e for rotatably supporting theshaft 1 c are provided to the compression mechanism 1 d on an upper endsurface side and a lower end surface side thereof.

(Electric Motor 1 b)

The electric motor 1 b includes the shaft 1 c having a lower end sideconnected to the bearings 1 e of the compression mechanism 1 d, therotor 3 to which the shaft 1 c is fixed and which is configured totransmit its own rotation to the shaft 1 c, and the stator 2 on whichwindings 6 a plurality of phases are wound. The shaft 1 c is fixed tothe rotor 3 at an upper side of the connection position of thecompression mechanism 1 d, and is configured to rotate along with therotation of the rotor 3, to thereby rotate the piston of the compressionmechanism 1 d. The rotor 3 includes a permanent magnet (not shown), andis rotatably supported by the shaft 1 c with a preset clearance from theinner side of the stator 2.

The stator 2 is configured to rotate the rotor 3, and is arranged sothat an outer peripheral surface of the stator 2 is fixed to an innerperipheral surface of the lower shell 1 a 2. The stator 2 includes acore 5 formed of a plurality of magnetic steel sheets or the like, theinsulator 7 mounted on the core 5, and the winding 6 wound in aplurality of layers on the core 5 via the insulator 7. The core 5 isformed by laminating a plurality of magnetic steel sheets into layersand arranging a plurality of those layers in an annular shape. Theinsulator 7 used for insulating between the windings 6 and the core 5 ismounted on the core 5.

The insulator 7 is formed of a resin, for example, so that the windings6 and the core 5 are insulated from each other. In this case, a side ofthe compression mechanism 1 d of the insulator 7 is referred to as aninsulator lower portion 7 a, and the side of the upper shell 1 a 1 ofthe insulator 7 is referred to as an insulator upper portion 7 b. Inother words, the portion positioned on the lower side of the lower endsurface of the core 5 is the insulator lower portion 7 a, and theportion positioned on the upper side of the upper end surface of thecore 5 is the insulator upper portion 7 b.

A cavity portion (not shown) is formed in the insulator upper portion 7b. Further, a mag-mate terminal 8 connected to a lead wire 9 to be usedfor supplying electricity in a U-phase, a V-phase, and a W-phase isembedded in the insulator upper portion 7 b. As illustrated in FIG. 2,the U-phase, the V-phase, and the W-phase are electrically connected toeach other via a jumper wire 10.

The windings 6 are wound in a plurality of layers on the core 5 via theinsulator 7. When current is supplied to the windings 6, the stator 2functions as an electromagnet, which interacts with the permanent magnetarranged in the rotor 3, to thereby produce the rotational force of therotor 3.

(Discharge Pipe 1 f)

The discharge pipe 1 f is a pipe for discharging high-temperature,high-pressure refrigerant that has been compressed by the compressionmechanism 1 d and that is in the airtight container 1. One end of thedischarge pipe 1 f is connected to a four-way valve (not shown) to beused for turning over (switching) passages. The other end of thedischarge pipe 1 f is connected to the upper shell 1 a 1 so as tocommunicate the interior with the exterior of the airtight container 1.

[Detailed Description of Stator 2]

FIG. 4 are schematic configuration example diagrams of the insulator 7and other members mounted on the stator 2. FIG. 5 are schematicconfiguration example diagrams of a state in which the winding 6 iswound on the insulator 7. Note that, FIG. 4(a) and FIG. 5(a) arediagrams illustrating the insulator 7 and the like are viewed from aninner peripheral surface side of the stator 2, FIG. 4(b) and FIG. 5(b)are diagrams illustrating the insulator 7 and the like viewed from alower side (the side of the compression mechanism 1 d) of the stator 2,FIG. 4(c) and FIG. 5(c) are diagrams illustrating the insulator 7 andthe like viewed from a side surface side of the insulator 7, and FIG.4(d) and FIG. 5(d) are diagrams illustrating the insulator 7 and thelike viewed from an upper side (he side of the upper shell 1 a 1) of thestator 2. The insulator 7 and the windings 6 are now described withreference to FIG. 4 and FIG. 5.

(Insulator 7)

The insulator 7 includes, in addition to the insulator lower portion 7 aand the insulator upper portion 7 b forming a part of the outerperipheral side of the insulator 7, a winding-base portion 7 c, which isa portion on which the windings 6 are wound, and an inner peripheralportion 7 d, which has an inner peripheral surface facing the outerperipheral surface of the rotor 3 and an outer peripheral surface facingthe windings 6. Note that, in the following description, the outerperipheral-side portion of the insulator 7, including the insulatorlower portion 7 a and the insulator upper portion 7 b, is referred to asan outer peripheral portion 7A.

Thus, the insulator 7 includes the outer peripheral portion 7A, thewinding-base portion 7 c, and the inner peripheral portion 7 d.

The winding-base portion 7 c has a radially inner side connected to theinner peripheral portion 7 d and a radially outer side connected to theouter peripheral portion 7A. The winding-base portion 7 c is formed soas to cover a part of a portion referred to as the tooth (not shown) ofthe core 5. In this case, the dimension from the right side to the leftside on the drawing sheet of FIG. 4(a) (the dimension from the upperside to the lower side in FIG. 4(b) and FIG. 4(d)) is the widthdimension. When the winding-base portion 7 c is viewed in aperpendicular cross-section, the dimension in the perpendiculardirection is longer than the width dimension, Therefore, the surface ofthe winding-base portion 7 c corresponding to the dimension in theperpendicular direction is defined as a longitudinal surface, and thesurface of the winding-base portion 7 c corresponding to the widthdimension is defined as a transverse surface.

A first transverse surface 7 c 1 (upper surface) forming a lower endsurface of the winding-base portion 7 c and a second transverse surface7 c 2 (lower surface) forming an upper end surface of the winding-baseportion 7 c are formed on the winding-base portion 7 c. Note that, thefirst transverse surface 7 c 1 and the second transverse surface 7 c 2are opposite surfaces to each other. Further, a first longitudinalsurface 7 c 3 (side surface) forming a side surface of the winding-baseportion 7 c and a second longitudinal surface 7 c 4 (side surface)formed at a position facing the first longitudinal surface 7 c 3 areformed on the winding-base portion 7 c. Note that, the firstlongitudinal surface 7 c 3 and the second longitudinal surface 7 c 4 areopposite surfaces to each other. Thus, the first transverse surface 7 c1, the second transverse surface 7 c 2, the first longitudinal surface 7c 3, and the second longitudinal surface 7 c 4 are formed as outerperipheral surfaces on the winding-base portion 7 c.

The first longitudinal surface 7 c 3 and the second longitudinal surface7 c 4 are formed at the end portions of the first transverse surface 7 c1 and the second transverse surface 7 c 2. On the first longitudinalsurface 7 c 3 and the second longitudinal surface 7 c 4, the windings 6are wound in parallel in a direction from the first transverse surface 7c 1 side toward the second transverse surface 7 c 2 side. On the otherhand, on one of the first transverse surface 7 c 1 and the secondtransverse surface 7 c 2, the winding 6 is wound at an angle in theradial direction of the stator 2, and the winding 6 of the inner layersand the winding 6 of the outer layers adjacent to the inner layers crosseach other. On the other of the first transverse surface 7 c 1 and thesecond transverse surface 7 c 2, the windings 6 are wound in parallel ina direction from the first longitudinal surface 7 c 3 side toward thesecond longitudinal surface 7 c 4 side. In other words, at one of thefirst transverse surface 7 c 1 and the second transverse surface 7 c 2,the pitch of the windings 6 is advanced by one.

The inner peripheral portion 7 d is formed so that the inner surface ofthe inner peripheral portion 7 d faces the outer peripheral surface ofthe rotor 3, and the outer peripheral surface of the inner peripheralportion 7 d faces the windings 6. The inner peripheral portion 7 d,which is connected to a portion of the winding-base portion 7 c that ison a radially inner side of the stator 2, is formed so as to extendvertically. The inner peripheral portion 7 d is used to ensure that thewindings 6 wound on the winding-base portion 7 c does not fall off.

(Windings 6)

The windings 6, which are wound in a plurality of layers around thewinding-base portion 7 c of the insulator 7, are formed of copper wire,for example. The windings 6 are wound in a manner such that the windings6 are offset from each other in a pitch direction for each turn aroundthe winding-base portion 7 c of the insulator 7. In this case, the pitchdirection is a direction parallel to a direction from the radially outerside of the stator 2 to the radially inner side of the stator 2. After agiven arbitrary layer of the winding 6 has been wound in an offsetmanner in the pitch direction from the radially inner side to theradially outer side, the next layer following the arbitrary layer iswound in an offset manner in the pitch direction from the radially outerside to the radially inner side. Then, the next layer after that layeris wound in an offset manner in the pitch direction from the radiallyinner side to the radially outer side. This operation is subsequentlyrepeated, and as a result, the windings 6 are wound on the insulator 7.For example, in FIG. 6 referred to below, the odd-numbered layers arewound from the radially inner side to the radially outer side, and theeven-numbered layers are wound from the radially outer side to theradially inner side.

In this case, the windings 6 may be wound by skipping one pitch or more.Further, the winding 6 wound in an offset manner from the radially innerside to the radially outer side and the winding 6 wound in an offsetmanner from the radially outer side to the radially inner side may bothbe present in the same layer. These specifics are described in moredetail below with reference to FIG. 6 to FIG. 8.

[Detailed Configuration of Windings 6]

FIG. 6 is an illustration of the winding 6 wound on the insulator 7 ofthe electric motor 1 b according to this embodiment. FIG. 7 is anillustration illustrating a first winding portion 6A of the winding 6illustrated in FIG. 6 and a gap 6C. FIG. 8 is an illustrationillustrating a second winding portion 6B of the windings 6 illustratedin FIG. 6. Note that, lines L illustrated in FIG. 6 indicate the rangewithin which the winding 6 is wound. The reason that the winding 6 iswound within this range is because if layers of the windings 6 arearranged beyond those lines, those layers interfere with the windings 6wound on an adjacent insulator 7, thus harming the reliability of theelectric motor 1 b. The configuration of the windings 6 is now describedin more detail with reference to FIG. 6 to FIG. 8.

FIG. 6 to FIG. 8 are cross-sectional diagrams of the winding 6 and theinsulator 7 in the plane parallel to the radial direction of the stator2. Further, the dotted lines illustrated in FIG. 6 and FIG. 7 indicatethe winding 6 that is wound on the first transverse surface 7 c 1 andthat is in the seventh layer of the windings 6. The winding 6 indicatedby the dotted lines is the first winding portion 6A wound from theradially outer side of the stator 2 to the radially inner side of thestator 2 so as to form the gap 6C dimensioned to one pitch or more ofthe winding 6 at a preset position.

Further, the winding 6 indicated by the thicker solid lines in FIG. 6and FIG. 8 is the second winding portion 6B, which is continuous fromthe first winding portion 6A and which is wound from the radially innerside of the stator 2 to the radially outer side of the stator 2 so as tofill in the gap 6C formed by the first winding portion 6A. Thus, thewinding 6 of the seventh layer is formed of the first winding portion 6Aand the second winding portion 6B. Note that, as illustrated in FIG. 6,the portion of the first winding portion 6A that is further to theradially inner side of the stator 2 than the gap 6C formed by the firstwinding portion 6A and the second winding portion 6B are wound to crosseach other. In other words, the second winding portion 6B is wound onthe outer side of the first winding portion 6A, and crosses the firstwinding portion 6A.

The thickness of the windings 6, which cross each other at the firstwinding portion 6A and the second winding portion 6B, increases in theshaft 1 c direction at the portion where the windings 6 cross eachother. In other words, when viewed in cross-section along the line A-A′in FIG. 6, the thickness of the second winding portion 6B (thicker solidlines in FIG. 6) increases in the shaft 1 c direction, which causes thesecond winding portion 6B to protrude from the seventh layer side towardthe eighth layer side. The thicker portion acts as a wall(anti-unwinding wall W) for suppressing unwinding of the windings 6 atthe winding start of the eighth layer.

Thus, the portion of the second winding portion 6B that is immediatelybefore the turnover (switch) to the eighth layer ((n+1)th layer)protrudes toward the eighth layer ((n+1)th layer) side at the positionat which the second winding portion 6B crosses the first winding portion6A to prevent the winding 6 immediately after the turnover (switch) tothe eighth layer ((n+1)th layer) from deviating to the radially innerside of the stator 2.

Various winding methods for the windings 6 are now described.

(1) Examples of the method of winding the windings 6 on the insulator 7of the stator 2 may include a concentrated winding method, in which thewinding 6 is wound on one insulator 7 in a concentrated manner, and adistributed winding method, in which the winding 6 is wound around aplurality of teeth. (2) The winding 6 wound on the insulator 7 have along side in a direction parallel to the shaft 1 c, and a short side ina direction orthogonal to the shaft 1 c. In winding the winding 6 on theinsulator 7, the windings 6 are offset in the radial direction of thestator 2 on any one of the long side and the short side. When thewindings 6 are offset on the long side of the insulator 7 (firstlongitudinal surface 7 c 3 and second longitudinal surface 7 c 4), thewindings 6 from two layers adjacent on the long side cross each other.This method is referred to as a long-side crossing method. On the otherhand, when the turns of winding 6 are offset on the short side of theinsulator 7, the winding 6 of one layer crosses the winding of a layeradjacent to the one layer on the short side. This method is referred toas a short-side crossing method. In the first embodiment, an example isdescribed in which the electric motor 1 b employs a concentrated windingand a short-side crossing method.

Note that, the winding 6 indicated by the thinner solid lines in FIG. 6is the winding 6 of the eighth layer, which is wound from the radiallyinner side of the stator 2 to the radially outer side of the stator 2.Thus, the winding 6 of the seventh layer (first winding portion 6A) andthe winding 6 of the eighth layer cross at the first transverse surface7 c 1. As a result, it can be seen that the electric motor 1 b employs ashort-side crossing method.

Also note that, in this embodiment, a case is described in which thewinding 6 is wound by advancing the pitch by one at the first transversesurface 7 c 1, which is one of the first transverse surface 7 c 1 andthe second transverse surface 7 c 2. However, the present invention isnot limited to this. The windings 6 only need to be advanced by onepitch for each turn, and hence, for example, the windings 6 may beadvanced by a ½ pitch at the first transverse surface 7 c 1 and a ½pitch at the second transverse surface 7 c 2. When the winding 6 isadvanced by a ½ pitch at the first transverse surface 7 c 1 and a ½pitch at the second transverse surface 7 c 2 _(;) the windings 6 ofadjacent layers on the inner side and the outer side cross each other atboth the first transverse surface 7 c 1 and the second transversesurface 7 c 2. Thus, the reason for winding the windings 6 of the innerlayers at an angle and winding the windings 6 of the outer layers at anangle so as to cross the inner layer is to increase the thickness of thewinding 6 in the shaft lc direction so that the windings 6 wound on theadjacent insulators 7 do not interfere with each other. In other words,the dimension of the shape of the winding 6 increases in a thicknessdirection to be similar to a cylindrical shape, in order to make iteasier to obtain a sufficient winding space factor.

Further, in this embodiment, an example employing a method in whichcrossing is on the short side is described. However, the gap 6C may alsobe formed on the long side by employing a method in which crossing is onthe long-side.

As illustrated in FIG. 6, the winding 6 is wound on the winding-baseportion 7 c of the insulator 7 for 11 layers. Further, the winding 6 isformed so that the number of turns decreases from the innermost layer tothe outermost layer. Specifically, from the first layer, which is theinnermost layer, to the seventh layer, the windings 6 are woundgenerally across the whole stator 2 (insulator 7) from the radiallyouter side to the radially inner side. From the eighth layer to theeleventh layer, the number of turns decreases as the layer numberincreases. For example, comparing the seventh layer and the eighthlayer, the number of turns is approximately 15 at the seventh layer,but, at the eighth layer, the number of turns is approximately 10, whichis approximately five turns less. Employing such a configurationprevents the windings 6 wound on the adjacent insulators 7 frominterfering with each other.

As illustrated in FIG. 6 to FIG. 8, the gap 6C is formed at anintermediate portion of the tooth, namely, at a position in anintermediate portion of the winding-base portion 7 c of the insulator 7.In this case, the term “intermediate portion” refers to a portionbetween the radially innermost side and the radially outermost side ofthe tooth (insulator 7), not to the radially innermost side and theradially outermost side of the tooth (insulator 7), but. Further, thegap 6C is formed at a position turning over (switching) from the seventhlayer to the eighth layer, In other words, the gap 6C is formed at aposition adjacent to the portion at which the seventh layer finishesbeing wound and the eighth layer starts being wound (see N in FIG. 8).

Thus, the gap 6C is formed at a position of an intermediate portion ofthe tooth in the radial direction of the stator 2, at which the winding6 is turned over (switches) from an n-th layer to an (n+1)th layer (nbeing an integer of 1 or more). However, the gap 6C is a portion that isfilled by the second winding portion 6B being wound therein. As aresult, when the electric motor 1 b has been manufactured, the gap 6C nolonger exists. Note that, in this embodiment, an example is described inwhich the gap 6C has a dimension of two pitches of the windings 6.

Next, the sequence for winding the winding 6 is described with referenceto FIG. 6 to FIG. 8.

The winding 6 of the seventh layer is wound from the radially outer sideof the stator 2 to the radially inner side of the stator 2 so as to formthe gap 6C dimensioned to one pitch or more at a preset position of thewindings 6 of the seventh layer. This step is referred to as a gapforming step. Specifically, the windings 6 are wound about ten times ina direction from the radially outer side of the stator 2 to the radiallyinner side of the stator 2 (see N-6 in FIG. 7). Next, the winding 6 iswound so as to form the gap 6C dimensioned to two pitches (see N-5 inFIG. 7), and then the windings 6 are further wound about two times fromthe radially outer side of the stator 2 to the radially inner side ofthe stator 2 (see N-3 and N-4 in FIG. 7).

Next, the windings 6 are wound from the radially inner side of thestator 2 to the radially outer side of the stator 2 so as to fill in thegap 6C formed in the gap forming step and so as to cross the windings 6wound in the gap forming step. This step is referred to as a gap fillingstep. Specifically, the windings 6 are wound two times in a directionfrom the radially inner side of the stator 2 to the radially outer sideof the stator 2 so as to fill in the gap 6C (see N-2 and N-1 in FIG. 8).As a result, the winding 6 wound in this gap forming step cross thewindings 6 wound in the gap forming step, causing the thickness of thewinding 6 to increase in the shaft lc direction at the crossing portion.The winding 6 indicated by N-1 act as a wall (anti-unwinding wall W) forsuppressing unwinding of the windings 6 at the winding start end of theeighth layer indicated by N.

The winding 6 of the eighth layer is wound immediately after the winding6 has been wound so as to fill in the gap 6C in the gap filling step.This step is referred to as a layer turnover step. Specifically, thewindings 6 are wound so that the start end of the windings 6 of theeighth layer abuts the windings 6 wound so as to fill in the gap 6Cformed in the gap filling step (see N in FIG. 8).

[Effects of Electric Motor 1 b According to this Embodiment]

FIG. 9 is an illustration regarding a related-art method of windingwindings. As illustrated in FIG. 9, for example, it can be seen thatthere is a position at which the start of the windings 6 of the eighthlayer, which is the portion at which layers of the winding 6 turn over(switch), crosses the windings 6 of the previous layer (seventh layer).At this position, the fixing force of the windings 6 is insufficient dueto the increased thickness as a result of crossing, and hence thewindings 6 at this position are susceptible to unwinding.

In this embodiment as well, the thickness of the windings 6 increases inthe shaft 1 c direction by winding the winding 6 of adjacent inner layerand outer layer on the first transverse surface 7 c 1 at an angle toeach other so that the windings 6 of both layers cross each other. Inthis case, the first winding portion 6A and the second winding portion6B cross each other, and the second winding portion 6B passes over apart of the first winding portion 6A. In other words, a portion of thesecond winding portion 6B is filled in the gap 6C, but the thickness ofthe portion of the second winding portion 6B crossing the first windingportion 6A increases in the shaft 1 c direction. Stated another way, thethickness of the turn of the winding 6 immediately before the windinglayer switches (see N-1 in FIG. 6) increases in the shaft 1 c direction.

As a result, the turn of the winding 6 at which the winding layerswitches (see N in FIG. 6) is wound on the insulator 7 while followingthe portion of increased thickness produced by the immediately previousturn of the windings 6 (see N-1 in FIG. 6). Further, the portion ofincreased thickness (or “increased thickness portion”) of theimmediately previous turn of the windings 6 (see N-1 in FIG. 6) servesas a wall (anti-unwinding wall W) for suppressing the turn of thewindings 6, at which the winding layer switches (see N in FIG. 6), fromunwinding toward the radially inner side of the stator 2. As a result,the electric motor 1 b according to this embodiment suppresses theoccurrence of unwinding. In such a winding arrangement, the turn of thewindings 6 indicated by N-1 and the turn of the winding 6 indicated byN-5 cross each other in the cross-section A-A′, and the thickness at thecrossing portion increases in the shaft direction. The increasedthickness portion of the winding 6 in the shaft 1 c direction indicatedby N-1 acts as an anti-unwinding wall W for suppressing the windings 6at the turn indicated by N in the cross-section A-A′ from unwindingtoward the radially inner side.

Further, the turn indicated by N-5 of the first winding portion 6Acrosses not only the turn indicated by N-1 of the second winding portion6B but also the turn indicated by N-2. As a result, even if the turnindicated by N of the winding 6, which is the start end of the eighthlayer, rises beyond the anti-unwinding wall W formed by the turnindicated by N-1 of the windings 6, unwinding past the winding 6indicated by N-2 toward the radially inner side is suppressed by theanti-unwinding wall W formed by the windings 6 indicated by N-2.

The electric motor 1 b according to this embodiment can suppress anincrease in the design complexity of the stator 2 without using a methodsuch as that disclosed in Patent Literature 1, in which the windings ofadjacent cores serve as an anti-unwinding wall.

In the electric motor 1 b according to this embodiment, the winding 6and the insulator 7 are not fixed to each other by, for example,impregnating the winding 6 and the insulator 7 with varnish, byintegrally molding the windings 6 and the insulator 7 together by resinmolding, or by adhering the windings 6 and the insulator 7 to each otherwith an adhesive or the like, and hence, an increase in manufacturingcosts can be suppressed by the amount that such a process may cost.

In this embodiment, an example is described in which the dimension ofthe gap 6C is equal to an amount of two pitches of the windings 6.However, the present invention is not limited to this. The gap 6C mayhave a dimension of one pitch or three or more pitches. Note that,increasing the dimension of the gap 6C has the benefit that it is easierto wind the windings 6, because the second winding portion 6B of thewindings 6 can be arranged more easily in the gap 6C. On the other hand,when the dimension of the gap 6C is decreased, it may be more difficultto wind the winding 6, because it is more difficult to arrange thesecond winding portion 6B of the windings 6 in the gap 6C. However, as aresult, the thickness of the windings 6 increases on the shaft 1 c side.There is thus the advantageous effect that unwinding of the winding 6 atthe winding start end of the eighth layer can be more reliablysuppressed.

REFERENCE SIGNS LIST

1 airtight container 1 a 1 upper shell 1 a 2 lower shell 1 b electricmotor 1 c shaft 1 d compression mechanism 1 e bearing 1 f discharge pipe1 g suction pipe 1 h container 2 stator 3 rotor 5 core 6 winding 6Afirst winding portion 6B second winding portion 60 gap 7 insulator 7Aouter peripheral portion 7 a insulator lower portion 7 b insulator upperportion

7 c winding-base portion 7 c 1 first transverse surface 7 c 2 secondtransverse surface 7 c 3 first longitudinal surface 7 c 4 secondlongitudinal surface

7 d inner peripheral portion 8 mag-mate terminal 9 lead wire 10 jumperwire 100 compressor W anti-unwinding wall

The invention claimed is:
 1. An electric motor including a stator, thestator including a core, the core including a tooth on which a windingis wound at a preset pitch to form a plurality of layers of the winding,the winding of one of the layers being angled to the winding of anotherone of the layers adjacent to the one of the layers, wherein an n-thlayer of the winding comprises: a first winding portion wound from aradially outer side of the stator to a radially inner side of the statorwith a gap between one turn and another at a preset position, the gapbeing dimensioned to one pitch or more of the winding; and a secondwinding portion wound from the radially inner side of the stator to theradially outer side of the stator in a continuous manner from the firstwinding portion to fill in the gap, the second winding portion crossingthe first winding portion, and the gap is at a position at anintermediate portion of the tooth in a radial direction of the stator,the position being a position at which the winding turns over from then-th layer to an (n+1)th layer, and a start end of the winding of the(n+1)th layer being in abutment with the winding wound to fill in thegap.
 2. The electric motor of claim 1, wherein a portion of the firstwinding portion, the portion being positioned at a radially inner sideof the gap on the stator, is wound crosswise to the second windingportion in the n-th layer of the winding.
 3. The electric motor of claim2, wherein the second winding portion crosses a portion of the firstwinding portion of the winding, the portion being wound to form the gapdimensioned to one pitch or more, and protrudes toward the (n+1)th layerside to form an anti-unwinding wall.
 4. The electric motor of claim 1,wherein the (n+1)th layer includes a smaller number of turns of windingthan the n-th layer.
 5. A compressor, comprising the electric motor ofclaim
 1. 6. A method of manufacturing an electric motor including astator, the stator including a core, the core including a tooth formedof a magnetic steel sheet on which a winding is wound at a preset pitchto form a plurality of layers of the winding, the winding of one of thelayers being angled to the winding of another one of the layers adjacentto the one of the layers, the method comprising: a gap forming step ofwinding the winding of an n-th layer from a radially outer side of thestator to a radially inner side of the stator so that a gap having adimension of one pitch or more is formed at an intermediate portion ofthe tooth in the radial direction of the stator in the winding of then-th layer; a gap filling step of winding the winding from the radiallyinner side of the stator to the radially outer side of the stator tofill in the gap formed in the gap forming step and cross the windingwound in the gap forming step; and a layer turnover step of winding thewinding with a winding start end of the winding of an (n+1)th layerbeing in abutment with the winding wound to fill in the gap formed inthe gap filling step.